Enable/Disable Alexa Voice Control

There is a way. Assuming OH 3 and UI created rules, create a Switch Item. When this Item is ON the commands from Alexa are allowed. When it’s off they are to be ignored.

Next create a Proxy Item for Alexa to command.

Then, create a rule that gets triggered when the Proxy Item is commanded that forwards that command to the “real” Item.

Finally, create a rule that triggers when the Switch Item from above changes. When it turns OFF, disable the rule that forwards the proxy commands to the “real” Item. When it turns ON enable the rule.

That essentially cuts off the commands from Alexa.

Use a Group and Design Pattern: Associated Items in the Proxy Item naming and you can create the rule that forwards the commands from Alexa in one rule.